Spectacle lenses (to be also referred to as lenses hereinafter) include different types such as a single-vision lens, a multifocal lens, and a progressive multifocal lens, and their diameters, outer diameters, lens powers, and the like differ from one lens type to another. Hence, a large number of types of lenses must be fabricated.
Conventionally, edging of such lenses is performed in accordance with the following procedure. For example, assume that a single-vision lens is to be edged. When the prescription lens is determined, if it is an ordinary prescription, a corresponding prescription lens is selected from the stock lenses (mass-production products of the regular inventories). If the prescription lens is a lens not available from the stock lenses (a custom-made article not available from the regular inventories), it is manufactured by the factory in accordance with the order. A stock lens has an upper surface (convex lens surface) and lower surface (concave lens surface) finished with predetermined lens curvatures (curves) on the basis of the optical design to have a predetermined lens power, and is completed until the final step of a surface process such as hardwearing coating or antireflection coating. Regarding a custom-made article, a lens material for it is prepared in advance in the form of a semi-finished product (semi-finished lens blank). The lens material is subjected to roughing-out, polishing, and the like in accordance with the ordered prescription power, and then to a surface process, so it is used as the prescription lens.
Once a prescription lens is manufactured, it is horizontally stored in a lens storing tray, together with a processing instruction slip, with its concave lens surface facing down, and is conveyed to an edging line. The operator takes out this prescription lens from the tray, places it on the inspection table of a predetermined inspecting unit such as a lens meter to check its lens power, cylinder axis, and the like. A processing center, the mounting angle of a processing jig (to be referred to as lens holder hereinafter) with respect to the lens, and the like (optical layout) are determined from the lens information, lens frame shape data, and prescription data about a wearer. On the basis of this information, the lens holder is mounted to the processing center of the lens (positioning). The lens holder is mounted on an edger together with the lens. The lens is edged by a grind stone or cutter, thereby processing the lens into a shape conforming to the shape of an eyeglass frame.
Conventionally, a layout for a lens and lens positioning with a lens holder, which are included in the pre-process for edging of the lens, are performed by an operator using specialized devices. This process is very inefficient and low in productivity, and hence becomes a serious hindrance to labor savings. In particular, an elastic seal is adhered to a lens holder so as to prevent damage to a lens and to hold the lens by this seal, and this adhering operation is cumbersome. In addition, since an operator must handle the lens with great care so as not to soil, damage, and break it, a significant burden is imposed on the operator.
For these reasons, demands have recently arisen for the development of an apparatus for single-vision lenses and multifocal lenses (APS; Auto Positioner for Single Vision Lens, and APM; Auto Positioner for Multi-focus Lens), which is designed to automatically perform a layout for a lens and lens positioning with a lens holder, thereby improving operation efficiency. In the present invention, this apparatus will be referred to as a layout block device.